The present invention relates to a method of preparing 17.alpha.-hydroxy and 17a.alpha.-hydroxy-D-homoetiocarboxylic acids.
According to the works of Miescher et al., Helv. 21: 1317 (1938), hydroxy-17-carboxylic acids of the androstane series, having an unnatural configuration at the C-17 carbon atom, can be produced in a three-stage process by the hydration of 17-cyanohydrin derivatives. In this method, the carbonitrile is treated in the first stage with hydrogen chloride/ethanol, thus forming the 3.beta.-acetoxy-17-hydroxy-5.alpha.-chloroandrostane-17-carboxylic acid amide.
In the second stage, the thus-formed hydroxyamide is refluxed with methanolic potassium hydroxide solution, thus obtaining the 3.beta.,17-dihydroxy-5-androstene-17-carboxylic acid amide. In the third stage, the dihydroxyamide is hydrolyzed to the free carboxylic acid with sodium propylate.
However, this process is disadvantageous in that the desired acid is obtained only in very low yields. However, recent experiments repeating this process were not very successful.